From June 2009 to June 2010 I had the privilege of Driving an All Electric MIMI E for a year, it was a great experience, and got me hooked on electric cars. I've since moved on to other electric cars which I will blog about.

Friday, February 6, 2009

Always on Regenerative Breaking

One of the best things about being in a field trial will be having direct access to the Engineers who designed and are testing the MINI E. BMW has stressed the importance of communication between the customer and technicians during this field trial. So far I havent talked to anyone from MINI/BMW but the salesman, I'm looking forward to questioning their technical people in more detail about the MINI E.
I keep thinking up new questions to as, going to write them down here to keep them all straight, and will let you know when I have answers.

I have some concerns about the regenerative breaking, the MINI E has an unusual system where when you release the gas petal ( need to change that to accelerator petal or something) the regenerative breaks kick in which is sort of like engine breaking. I think I understand why they did this having the wheels directly tied to the motor is technically a lot simpler then having to put the car in neutral when you release the accelerator, in a Gas car the engine is always running so you dont notice any breaking effect unless your engine is at very high RPM or your going down hill in a low gear.
But I worry about this always on Regenerative breaking for a few reasons, coasting without breaking or accelerating is one of the first tricks hypermilers practice, regenerative breaking gives you back energy but no where near what it takes to get to back up to speed. I worry that I'll be releasing my foot of the petal and breaking when I dont really want to, I find people who ride the breaks very annoying to drive behind.
Then there is safety, one trick a safe driver knows is when your on an icy road or hydroplanning the last thing you want to do is put on the break this will send the car out of control, you need to release the accelerator, and let the car coast down in speed slowly, I wonder what the best practice for controlling the MINI E when you lose traction, Im guessing keep your foot on the accelerator, but just barely, maybe that will slow it down.


  1. In the latest Road & Track magazine, there is a comparison of plug-in electrics. One of the cars is the AC Propulsion eBox (a converted Scion xB) which has essentially the same electric motor/battery combination used in the Mini E (makes sense since AC supplies the motor and batteries to Mini for the conversion to electric). Anyway, the eBox has a dash mounted lever so that the driver can control the amount of regenerative braking that takes place, from none to max. I wonder if Mini considered this approach. The article is located here:

    A question I have is if the brake lights comes on during regenerative braking? This could be a safety concern if drivers behind you don't anticipate the Mini slowing down as fast as it will without the driver even braking.
    I too was chosen for the field trial here in the Los Angeles area, as long as there isn't a problem with the garage inspection. I can't wait to get the car! My dealer said some cars may be delivered as early as March and they will trickle in over the next few months. I look forward to your blog updates.

  2. Great article Stan
    I've made a link to it here: road and track

    I'd prefer if the amount of regeneration was based on how hard you pressed on the brake petal, but I guess thats not as simple as it sounds

    Keep in touch, you'll probably get yours on the West coast befor us on the East, so let us know how it goes.